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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Subject: [PATCH 5.4 087/108] usb: dwc2: gadget: Fix sending zero length packet in DDMA mode.
Date:   Mon, 26 Jul 2021 17:39:28 +0200
Message-Id: <20210726153834.468412085@linuxfoundation.org>
In-Reply-To: <20210726153831.696295003@linuxfoundation.org>
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From: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>

commit d53dc38857f6dbefabd9eecfcbf67b6eac9a1ef4 upstream.

Sending zero length packet in DDMA mode perform by DMA descriptor
by setting SP (short packet) flag.

For DDMA in function dwc2_hsotg_complete_in() does not need to send
zlp.

Tested by USBCV MSC tests.

Fixes: f71b5e2533de ("usb: dwc2: gadget: fix zero length packet transfers")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Link: https://lore.kernel.org/r/967bad78c55dd2db1c19714eee3d0a17cf99d74a.1626777738.git.Minas.Harutyunyan@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/dwc2/gadget.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -2748,12 +2748,14 @@ static void dwc2_hsotg_complete_in(struc
 		return;
 	}
 
-	/* Zlp for all endpoints, for ep0 only in DATA IN stage */
+	/* Zlp for all endpoints in non DDMA, for ep0 only in DATA IN stage */
 	if (hs_ep->send_zlp) {
-		dwc2_hsotg_program_zlp(hsotg, hs_ep);
 		hs_ep->send_zlp = 0;
-		/* transfer will be completed on next complete interrupt */
-		return;
+		if (!using_desc_dma(hsotg)) {
+			dwc2_hsotg_program_zlp(hsotg, hs_ep);
+			/* transfer will be completed on next complete interrupt */
+			return;
+		}
 	}
 
 	if (hs_ep->index == 0 && hsotg->ep0_state == DWC2_EP0_DATA_IN) {